Using an unified standard bus structure makes it easier to interconnect different equipment and also allows for convenient expansion of components and equipment. A type of inter-integrated circuit (also known as I2C or Inter-IC) bus developed by Philips company is used as a first level internal serial bus for integrated circuits. Compared to the conventional parallel bus system, there are fewer transmission lines between the main controller and each peripheral component or slave device. The three lines include a serial data line SDA, a serial clock line SCL, and a ground GND. The I2C bus has a strong anti-interference ability, fast speed, and it is easy to allow for system expansion as well as to standardize modular design. However, the conventional stepper motor, including the driver integrated circuit of the stepper motor for a cellular phone photo module driver control system, has yet to be equipped with the I2C serial bus; instead, it uses a parallel input which has more signal ends resulting in more input contact points with the chip and thus occupying significant chip area and limiting application of the driver integrated circuit to have certain space requirement. Moreover, the driver integrated circuit that uses the parallel connection needs to take up the main controller input and output connections. Since the number of input and output connections in the main controller are limited, additional expansion components are required for the conventional stepper motor resulting in cost increase.